Ion trap analyzer and ion trap mass spectrometry analysis method

Abstract

An ion trap analyzer, an ion trap mass spectrometry analysis method, and an ion fragmentation method are provided. The ion trap analyzer includes an ion trapping space enclosed by multiple electrodes (101, 102, 103, 11, 12, 214), where a high-frequency voltage is applied on at least a part of the electrodes, so as to generate, within the trapping space, a trapping electric field dominated by a quadratic field. The apparatus is provided with an ion ejection outlet (200) in at least one direction away from the center of the trap; an alternating voltage signal used for resonant excitation of ion motions is overlaid on an electrode part that is on a side of the ion ejection outlet and closest to the ejection outlet, while no voltage signal that is identical in range and phase with the alternating voltage is applied on at least one remaining electrode part in said direction. With the method, or by further applying, to the remaining electrode part in said direction, a voltage signal that is inverted to the alternating voltage, the orientation of an alternating electric field induced by the excitation alternating voltage signal can be limited, thereby improving the resonance ejection efficiency of the ion trap, reducing, in ion motions, motion coupling between an ejection direction and a non-ejection direction, and improving the viability of selecting the ion trap as a mass analyzer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a National Stage of International Application No. PCT / CN2013 / 000345 filed Mar. 26, 2013, claiming priority based on Chinese Patent Application No. 201210093413.X filed Mar. 31, 2012, the contents of all of which are incorporated herein by reference in their entirety.BACKGROUND[0002]1. Technical Field[0003]The present invention relates to a technology of performing mass spectrometry analysis on ions by using an ion trap, and in particular, to an ion trap analyzer optimized by an auxiliary excitation electric field.[0004]2. Related Art[0005]Since 1953 when Paul invented the three-dimensional quadrupole ion trap technology, as an important part of the mass spectrometry technology, ion traps together with related mass spectrometry technologies are widely used in qualitative and quantitative testing of trace materials and material structure information testing based on fragment dissociation spectra, and are used as ion flow...

AI Technical Summary

Benefits of technology

[0014]Different from the prior art described above, an objective of the present invention is to correct, mainly by limiting an applying range of an alternating excitation voltage, a field pattern of an excitation electric field formed by the excitation voltage, so that the excitation voltage is mainly applied on an area near an ejection outlet of a confining electrode in a direction of the ejection outlet. For other electrode parts in this direction, no resonant excitation voltage signal that has the same phase as the alternating excitation voltage is applied. Therefore, the amplitude of the excitation voltage increases rapidly near the ion ejection outlet, so that ions having a large enough ion motion range are directly accelerated, resonate, and are ejected when getting close to the ejection outlet of the ion trap; because resonance of the ions is not detuned by the negative high-order field near the ejection outlet, the motion range of the ions is not reduced, and no random ejection delay occurs. Therefore, the mass resolution performance of an ion trap mass analyzer using the technology of the present invention is improved.

[0015]The advantage as compared with the prior art lies in that: compared with an RF trapping voltage which easily reaches thousands of volts, the excitation voltage generally requires a small voltage amplitude (generally less than 50 V, and usually less than 10 V); therefore, the amplitude adjustment of the excitation voltage can be directly initiated by a medium speed digital-to-analog converter, and implemented by using a medium-speed operational amplifier integrated circuit and by amplifying the voltage along with the current, which, compared with the adjustment of a high trapping voltage, reduces circuit and commissioning complexity for overall voltage adjustment caused by nonlinearity of a high-voltage amplification circuit and various devices under a high voltage, and therefore, also reduces power consumption.

Problems solved by technology

Such damage is mainly caused by the fact that when the vibration amplitude of ions increases, the restoring force sensed by on the ions is smaller than the force of the simple harmonic potential trap due to the existence of the high-order negative field, and consequently, the resonance frequency of the ions has a red shift, and the resonance of ion motions is detuned.

In any case, the added high-voltage power supply increases the complexity of an instrument; especially, when these high-voltage power supplies are expected to be adjusted discretely, the circuits thereof are even more complex.

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